U.S. Overestimates Peril of Radon in Homes, New Study Says

AP

Published: March 29, 1991

PHOENIX, March 28—
A new study suggests that Americans are exposed to only about a third as much radon inside their homes as monitoring devices indicate, and that many have probably spent money needlessly to get rid of the gas.

The Environmental Protection Agency has recommended that homeowners put radon monitors in their basements, where levels of the odorless gas are probably the highest. But the study, presented here Wednesday at a meeting sponsored by the American Cancer Society, concluded that human exposure was about 30 percent of the radon levels found in the basements. It is the first study to see how much radon people are exposed, as opposed to how much is found in part of a house.

"I don't think you should remediate a home based on basement levels," said Dr. Naomi H. Harley, a radiological expert at New York University Medical Center, who conducted the study. "A single basement reading is not representative of personal exposure." A Cause of Lung Cancer

Radon, released in the decay of radium, is present in soils and rocks in many places and can seep into homes, reaching dangerous levels in unventilated spaces. The environmental agency estimates that radon gas causes 20,000 cases of lung cancer a year in the United States. The figure is based on lung cancer rates among miners who are exposed to high levels.

The agency has recommended that vents and fans be installed in homes with high levels. This work costs about $1,000. Based on basement readings, the agency has estimated that about 20 percent of homes in the United States should have radon vents.

"It's just not believable that there are that many homes that need remediation," Dr. Harley said. Based on her study, she said the figure would be about 7 percent.

A spokeswoman for the environmental agency, Martha Casey, said officials there had not seen Dr. Harley's study. "We certainly are very willing to examine these studies," she said. "And we may eventually revise our risk estimate numbers." 52 Houses Studied in Illinois

Dr. Harley's study was conducted in 52 houses in DuPage County, Illinois. Family members wore personal monitors, which were developed for the study, and also placed ordinary radon detectors in rooms throughout their homes.

Participants wore the monitors at all times for about three weeks. Dr. Harley found that stationary detectors on the first floor recorded the most accurate radon levels in the house. But personal exposure was only about 70 percent of these first-floor readings.

Dr. Harley said her personal radon monitors were not commercially available. The room testers are widely sold, typically for $10 to $20. She recommended that they be placed in the first-floor living area. An exception, she said, is basement bedrooms.

The environmental agency has recommended that corrective action be taken in homes where where there are more than 4 picocuries of radon per liter of air. Extended exposure to concentrations above 20 picocuries per liter of air poses a far greater risk, the agency says, warranting corrective action within months. And at levels above 200 picocuries per liter, immediate measures are called for.

Of 100 people spending 75 percent of their time for 70 years in a house with 4 picocuries of radon per liter of air, 1 to 5 would die of lung cancer as a result, the agency says.